PUBLICATION

Valproic Acid silencing of ascl1b/ascl1 results in the failure of serotonergic differentiation in a zebrafish model of Fetal Valproate Syndrome

Authors
Jacob, J., Ribes, V., Moore, S., Constable, S.C., Sasai, N., Gerety, S.S., Martin, D.J., Sergeant, C.P., Wilkinson, D.G., and Briscoe, J.
ID
ZDB-PUB-131119-20
Date
2014
Source
Disease models & mechanisms   7(1): 107-17 (Journal)
Registered Authors
Wilkinson, David
Keywords
Serotonin, Fetal valproate syndrome, Zebrafish, Notch, Proneural gene, Hdac1
MeSH Terms
  • Serotonin/metabolism
  • Receptors, Notch/metabolism
  • Zebrafish
  • Zebrafish Proteins/genetics
  • Zebrafish Proteins/metabolism*
  • Valproic Acid/adverse effects*
  • Valproic Acid/metabolism
  • Child Development Disorders, Pervasive/genetics
  • Cell Differentiation
  • Basic Helix-Loop-Helix Transcription Factors/genetics
  • Basic Helix-Loop-Helix Transcription Factors/metabolism*
  • Transgenes
  • Animals
  • Histone Deacetylase 1/metabolism
  • Anticonvulsants/chemistry
  • Disease Models, Animal
  • Signal Transduction
  • Abnormalities, Drug-Induced/genetics*
  • Abnormalities, Drug-Induced/metabolism
  • Neurons/metabolism
  • Gene Silencing*
  • Homeostasis
  • Epigenesis, Genetic
(all 23)
PubMed
24135485 Full text @ Dis. Model. Mech.
Abstract

Fetal valproate syndrome (FVS) is caused by in utero exposure to the drug sodium valproate. Valproate is used worldwide for the treatment of epilepsy, as a mood stabiliser and for its pain relieving properties. In addition to birth defects, FVS is associated with an increased risk of autism spectrum disorder (ASD), which is characterised by abnormal behaviours. Valproate perturbs multiple biochemical pathways and alters gene expression through its inhibition of histone deacetylases. Which, if any, of these mechanisms is relevant to the genesis of its behavioural side-effects is unclear. Neuroanatomical changes associated with FVS have been reported and amongst these, altered serotonergic neuronal differentiation is a consistent finding. Altered serotonin homeostasis is also associated with autism. Here we have used a chemical-genetics approach to investigate the underlying molecular defect in a zebrafish FVS model. Valproate causes the selective failure of zebrafish central serotonin expression. It does so by downregulating the proneural gene ascl1b, an ortholog of Ascl1 and a known determinant of serotonergic identity in the mammalian brainstem. Ascl1b is sufficient to rescue serotonin expression in valproate treated embryos. Chemical and genetic blockade of the histone deacetylase Hdac1 downregulates ascl1b, consistent with the Hdac1 mediated silencing of ascl1b expression by valproate. Moreover, tonic Notch signalling is critical for ascl1b repression by valproate. Concomitant blockade of Notch signalling restores ascl1b expression and serotonin expression in both valproate-exposed and hdac1 mutant embryos. Together these data provide a molecular explanation for serotonergic defects in FVS and highlight an epigenetic mechanism for genome-environment interaction in disease.

Genes / Markers
Figures
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Expression
Phenotype
Mutations / Transgenics
Allele Construct Type Affected Genomic Region
nim10TgTransgenic Insertion
    s436
      Point Mutation
      ta52b
        Point Mutation
        1 - 3 of 3
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        Human Disease / Model
        Human Disease Fish Conditions Evidence
        fetal valproate syndromeWTchemical treatment: pharmaceuticalTAS
        1 - 1 of 1
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        Sequence Targeting Reagents
        No data available
        Fish
        1 - 4 of 4
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        Antibodies
        Orthology
        No data available
        Engineered Foreign Genes
        Marker Marker Type Name
        GAL4EFGGAL4
        RFPEFGRFP
        1 - 2 of 2
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        Mapping
        No data available